Hotmelt adhesive

ABSTRACT

A hotmelt adhesive based on a number of components is provided. One of the components is at least one polyamide based on dimerized fatty acid, said polyamide being present in an amount by weight of the composition of at least 50%. Another component is from at least one ethylene copolymer selected from the group consisting of ethylene/vinyl acetate, ethylene/acrylate, said acrylate being derived from an alcohol containing 1 to 18 carbon atoms, and ethylene/methacrylate, said methacrylate being derived from an alcohol containing 1 to 18 carbon atoms, said ethylene copolymer being present in an amount by weight of the composition of 5 to 20%. Another component is at least one copolymer of styrene with one or more members selected from the group consisting of ethylene, isoprene and butylene, said copolymer of styrene being present in an amount by weight of the composition of 2 to 10%. Another component is at least one plasticizer, said plasticizer being present in an amount by weight of the composition of 5 to 25% by weight. Optional components are 0 to 10% by weight of at least one tackifying resin from the group consisting of polycyclopentadiene, polyterpene, liquid hydrocarbon resin and 0 to 15% by weight of at least one copolymer of monomers selected from the group consisting of ethylene, propylene, butylene and maleic anhydride.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a hotmelt adhesive, to its production and useand to moldings produced with the hotmelt adhesive.

2. Discussion of Related Art

Hotmelt adhesives are adhesives solid at room temperature which aretemporarily melted to perform their adhesive function. They are basedessentially on polyamides, polyolefins or polyesters and mixturesthereof. By incorporation of additives, they can be further optimizedfor the particular applications envisaged.

Thus, a hotmelt adhesive for bonding non-pretreated polyethylene andcopper in accordance with DE-OS 35 04 804 consists essentially of thefollowing compatible components:

a) polyamides based on dimerized fatty acids, aliphatic amines andmodifying additives,

b) copolymers of ethylene, the inner anhydride of an ethylenicallyunsaturated dicarboxylic acid and optionally (meth)acrylates and/orvinyl esters and

c) other auxiliaries such as, for example, compatibility promoters andtackifiers.

Although ethylene or propylene can be bonded with high strength valuesby compositions such as these without any need for the otherwise usualpretreatment and although the low-temperature properties are stillremarkably good at -20° C. and lower, the known hotmelt adhesives havethe following disadvantage: their softening points are too high, forexample for the processing of shrunk articles. Softening points of <130°C. are generally required for this application.

EP-A1-0 040 926 also describes a hotmelt adhesive for bonding untreatedpolyethylene. This known hotmelt adhesive contains

a) a polyamide based on one or more dimeric fatty acids,

b) an ethylene/acrylic acid/butyl acrylate terpolymer containing freecarboxyl groups and optionally

c) an acrylic rubber preferably in the form of a copolymer of ethylacrylate, butyl acrylate, methoxyethyl acrylate and ethoxyethylacrylate.

The document in question does not provide any information on theviscosity and softening point of the hotmelt adhesive so that it maywell be that the products described are unsuitable for certainapplications, for example for the processing of shrunk articles. Foradhesion to non-pretreated polyethylene, it is important to bear in mindthat, in many cases, not only high strengths, but also a balanced ratioof adhesion to substrate surface/inner cohesion is required so that,besides high strength values, a cohesive fracture pattern is alsoobtained in peel tests. None of this is mentioned in EP-A1-0 040 926.

U.S. Pat. No. 4,552,819 describes a hotmelt adhesive for coatingshrinkable moldings of polyethylene for the electrical industry, moreparticularly the cable industry, which contains the followingcomponents:

a) 5 to 30% by weight of a polyamide based on dimerized fatty acids withan amine value of 0.5 to 15,

b) 50 to 90% by weight of an ethylene/vinyl acetate copolymer which ishydrolyzed according to the statement of invention, but not in thecomparative tests,

c) 5 to 30% by weight of a block copolymer of styrene/butadiene/styreneor styrene/isoprene/styrene and optionally

d) tackifiers, such as terpene, terpene/phenol and alkylphenol resin.

This composition has the disadvantage that adhesion to non-pretreatedpolyethylene cannot be obtained. In addition, the softening points aretoo high.

Finally, EP-A1-0 079 178 describes a hotmelt adhesive for bondingnon-pretreated polyethylene which has the following composition:

a) copolymer of ethylene and α,β-unsaturated carboxylic acid and/or analkyl ester thereof and vinyl acetate where the copolymer does notcontain any alkyl ester units,

b) copolymer of ethylene and unsaturated carboxylic acid.

The composition may also contain thermoplastics, such as polyethylenefor example. Compositions such as these have the disadvantage that theylack sufficient resistance to chemicals.

DE-OS 23 47 799 describes heat-resilient moldings of crosslinkedpolyethylene with at least one layer of a hotmelt adhesive of thefollowing composition:

a) polyamide based on dimerized fatty acid,

b) acidic ethylene copolymers with an acid value of around 3 to 80 and

c) a tackifier, more particularly a polyketone resin.

This hotmelt adhesive has the disadvantage of inadequate adhesion tonon-pretreated polyethylene.

DESCRIPTION OF THE INVENTION

This invention relates to a hotmelt adhesive comprising:

a) at least 50% by weight of at least one polyamide based on dimerizedfatty acid,

b) 5 to 20% by weight of at least one ethylene copolymer selected fromthe group consisting of ethylene/vinyl acetate, ethylene/acrylate, saidacrylate being derived from an alcohol containing 1 to 18 carbon atoms,and ethylene/methacrylate, said methacrylate being derived from analcohol containing 1 to 18 carbon atoms,

c) 2 to 10% by weight of at least one copolymer of styrene with one ormore members selected from the group consisting of ethylene, isopreneand butylene,

d) 5 to 25% by weight of at least one plasticizer,

e) 0 to 10% by weight of at least one tackifying resin from the groupconsisting of polycyclopentadiene, polyterpene, liquid hydrocarbon resinand

f) 0 to 15% by weight of at least one copolymer of monomers selectedfrom the group consisting of ethylene, propylene, butylene and maleicanhydride.

The problem addressed by the invention was to remedy the situationdescribed above.

The invention is defined in the claims and lies essentially in thechoice of the components listed.

DETAILED DESCRIPTION OF THE INVENTION

The hotmelt adhesive according to the invention contains at least 50% byweight of at least one polyamide based on dimerized fatty acid as itskey component. "Dimerized fatty acids" are obtained by the coupling ofunsaturated long-chain monobasic fatty acids, for example linolenicacid, oleic acid. It is a mixture of several isomers (see R. F. Paschke,L. E. Peterson and D. H. Wheeler, Journal of the American Oil Chemist'sSociety, 41, 723 (1964). Trimers and other oligomers may of course alsobe present in small amounts. The acids have long been known and arecommercially available.

The polyamides according to the invention preferably have the followingcomposition:

up to 55 mole-% and, more particularly, 35 to 49.5 mole-% of dimerizedfatty acid,

up to 15 mole-% and, more particularly, 0.5 to 15 mole-% of at least onemonomeric fatty acid containing 12 to 22 carbon atoms and

up to 35 mole-% and, more particularly, 2 to 35 mole-% of at least onepolyether diamine corresponding to the following general formula:

    H.sub.2 N--R.sub.1 --O--(R.sub.2 O).sub.x --R.sub.3 --NH.sub.2(I)

x is a number of 8 to 80, mainly from 8 to 40,

R₁ and R₃ may be the same or different and represent aliphatic and/orcycloaliphatic hydrocarbon radicals preferably containing 2 to 8 carbonatoms,

R₂ is an optionally branched aliphatic hydrocarbon radical containing 1to 6 carbon atoms,

and

up to 48 mole-% and, more particularly, 15 to 48 mole-% of at least onealiphatic and/or cycloaliphatic diamine containing 2 to 40 carbon atoms,up to two thirds of the dimerized fatty acids being replaceable byaliphatic dicarboxylic acids containing 4 to 12 carbon atoms.

Another favorable embodiment is characterized by the use of a polyamideobtained from:

up to 55 mole-% and, more particularly, 35 to 49.5 mole-% of dimerizedfatty acid,

up to 15 mole-% and, more particularly, 0.5 to 15 mole-% of at least onemonomeric fatty acid containing 12 to 22 carbon atoms and

up to 55 mole-% and, more particularly, 45 to 55

mole-% of at least one C₂₋₄₀ amine containing at least two primaryand/or secondary amino groups, up to two thirds of the dimerized fattyacids being replaceable by aliphatic dicarboxylic acids containing 4 to12 carbon atoms.

In addition, the polyamides used in accordance with the invention maycontain other raw materials typically encountered in hotmelt adhesives.Thus, aliphatic dicarboxylic acids in particular are typical ingredientsof hotmelts. Suitable aliphatic carboxylic acids preferably contain 4 to12 carbon atoms. For example, glutaric acid, maleic acid, succinic acid,adipic acid, pimelic acid, suberic acid or even sebacic acid aresuitable carboxylic acids. Up to two thirds of the molar quantity of thedimer fatty acid may be replaced by these acids. It is known to theexpert in this regard that the melting point of polyamides can beincreased within certain limits by addition of sebacic acid. Otherpossible raw materials for hotmelt adhesives are long-chainaminocarboxylic acids, such as 11-aminoundecanoic acid or even lauryllactam. The polyamide raw materials known in fiber chemistry, such ascaprolactam for example, may also be used in small quantities. Thesematerials enable the expert to increase the melting point within certainlimits.

So far as the amine components in the polyamides are concerned, it ispointed out that polyether polyols terminated by primary amino groupsare preferred. Suitable amino-terminated polyether polyols are based onpolyethylene glycol, polypropylene glycol or polytetrahydrofuran.Amino-terminated polyether polyols with little or no solubility in waterare preferred. The amino-terminated polyether polyols used havemolecular weights of 700 to 3,500 or even from 1,200 to 2,500. Aparticularly suitable class of raw materials are, for example,bis-(3-aminopropyl)-polytetrahydrofurans with a molecular weight of 700to 3,500 and bis-(2-aminopropyl)-polyoxypropylenes with a molecularweight of 1,200 to 2,500. Primary linear alkylenediamines containing 2to 10 carbon atoms, such as for example hexamethylenediamine,1,3-diaminopropane, 1,4-diaminobutane, may also be used. Piperazine,tallow diamine and dipiperidyl propane are also suitable.

Another suitable class of diamines is derived from dimer fatty acids andcontains primary amino groups instead of the carboxyl groups. Substancessuch as these are often called dimer diamines. They are obtained bynitrile formation from the dimerized fatty acids and subsequenthydrogenation.

The following observations apply to the molecular structure of thepolyamides on which the compatible mixtures according to the inventionare based. It is known to the expert in this field that monofunctional,difunctional and trifunctional raw materials have to be used in acertain ratio to obtain fusible, i.e. uncross-linked products. Generalspecialist knowledge of polymer chemistry is relevant in this regard.Accordingly, in the event of crosslinking/gelation, formulations with notendency towards gelation can be obtained by reducing the percentagecontent of trifunctional components (trimer fatty acids) and/orincreasing the content of monofunctional amines or fatty acids. Themolecular weight of the hotmelt adhesives according to the invention canbest be calculated by terminal group titration of the terminal amino oracid groups via the molecular weight of the individual components.Preferred hotmelt adhesives according to the invention contain only onetype of functional terminal groups, i.e. they are amines or carboxylicacids. For example, polyamides with a residual acid value have favorableproperties. The residual acid value is in the range from 1 to 50,preferably in the range from 2 to 30 and more preferably in the rangefrom 4 to 12. However, amino-terminated polyamides are preferred formany applications. They have amine values of 2 to 15 and preferably 4 to10.

The "ethylene copolymer" component crucial to the invention may be acopolymer of ethylene and vinyl acetate. Copolymers such as these areknown and are commercially available. They preferably contain 14 to 40%of vinyl acetate and have a melt index of 25 to 2,500.

Among copolymers of ethylene and acrylate or methacrylate, the followingesters are of particular importance: methyl, ethyl, propyl, butyl,2-ethylhexyl esters and esters with so-called fatty alcohols containing12 to 18 carbon atoms which may even be unsaturated. The (meth)acrylatemay even be partly replaced by esters of vinyl alcohol, for examplevinyl acetate, or by vinyl esters of C₃₋₁₈ carboxylic acids. Up to 15mole-% of the ethylene may be replaced by propylene. Ethylene copolymersof 80 to 90% by weight of ethylene and 10 to 20% by weight of(meth)acrylates are preferably used. In general, the ester is used insmaller quantities, the longer alcohol component. Their molecular weight(weight average) is preferably in the range from about 50,000 to250,000. The copolymers of ethylene and (meth)acrylates are also knownper se. They may be prepared in the usual way by radical polymerization.

The third key component is at least one copolymer of styrene withethylene, isoprene and/or butylene. The copolymers in question arepreferably thermoplastic elastomers of block polymers with styrene inthe hard polymer segment and butadiene or isoprene and preferablyethylene and butylene in the soft polymer segments. Accordingly, thestyrene-ethylene/butylene-styrene block polymer is preferred. Itpreferably has the following composition and properties: 14 to 29% ofstyrene; 71 to 86% of elastic components. By virtue of its two-phasestructure, two glass transition temperatures are observed in contrast tostatistical copolymers. Other advantages include high strength, highelasticity and high resilience and also flexibility at low temperatures.This component is also known per se and is commercially available.Substances which reduce the glass transition temperature, the elasticproperties and hardness are used as plasticizers (plasticizingcomponents). The plasticizer used is at least one substance from theclasses of, for example, phthalic acid esters, hydroxycarboxylic acidesters and polymer plasticizers. Phthalic acid esters, hydroabietylalcohol or polybutene are preferably used. The hydroabietyl alcohol is ahigh molecular weight primary alcohol of a hydrogenated colophony acid.It is commercially available under the name of Abitol from the Herculescompany. The polybutene is an isobutylene/butene copolymer which isproduced from generally high molecular weight monoolefins of lowisoparaffin content. The phthalic acid esters are, for example,ULTRAMOLL PP (a phthalic acid polyester) or CELLOLYN 21 (a phthalateester of technical hydroabietyl alcohol obtainable from Hercules).

In some cases, it has proved to be of advantage to add at least onetackifying resin. In the context of the invention, a "tackifying resin"is understood to be a resin which makes the composition tacky so thatother articles adhere firmly to it after light pressure has been brieflyapplied. They themselves do not have to be tacky at room temperature.They generally have relatively low molecular weights of around 200 to2,000 and a high non-uniformity. Substances belonging to the followingclasses are suitable: colophony and its derivatives and also petroleumresins, more particularly polycyclopentadiene, polyterpene and liquidhydrocarbon resin. Specific commercial products are, for example,SYNTHALAT DR 585-806 and TENREZ G 304 (triethylene glycol ester ofcolophony obtainable from Erbsl oh), ABALYNE (a methyl ester ofcolophony obtainable from Hercules), HERCOLYN D and HERCOLYN DE(hydrogenated methyl esters of colophony obtainable from Hercules),PICCOVAR L 30 and L 60 (aromatic hydrocarbons obtainable from Hercules)and ESCOREZ 2520 (a liquid hydrocarbon obtainable from Exxon).

An addition of at least one copolymer of ethylene, propylene or butyleneand/or maleic anhydride can also be of advantage. The hotmelt adhesivepreferably contains 2 to 8% by weight of resin and 2.5 to 10% by weightof a copolymer of ethylene and maleic anhydride.

The composition according to the invention is a compatible polymermixture. Mixtures are regarded as "compatible" if they appearhomogeneous to the eye, i.e. consist of one phase, in the solid stateand up to the processing temperature lying beyond the melting point.Physically, they are either true solutions or fine-particle dispersionsof one polymer in a matrix of the other. An indication of homogeneity isthe observation of only one glass temperature (Tg) in a DSC diagram(rate: 15° C./min.; second run; starting temperature: -120° C.; finaltemperature: 300° C.). If only one glass temperature is observed, thecomposition is always "homogeneous" in the context of the invention.However, several glass temperatures may also occur.

In addition to the constituents mentioned above, the adhesives accordingto the invention may contain other typical auxiliaries. Thus,antioxidants, light and heat stabilizers, fillers, pigments,preservatives or fungicides may be added in small quantities. Theseauxiliaries are typically added in a quantity of 0.5 to 2% by weight.

All percentages by weight are based on the final hotmelt adhesive.

The adhesive according to the invention has the following physicalproperties:

The hotmelt adhesives soften at temperatures in the range from 90° to140° C. and preferably at temperatures in the range from 90° to 110° C.Their melt viscosities at 160° C. are mainly in the range from 10,000 to180,000 mPa.s and preferably in the range from 20,000 to 100,000 mPa.s.Their heat resistance is generally above 60° C. and preferably above 80°C.

Although compatible mixtures of the components according to theinvention are safely obtained in the claimed range, the expert may haveto verify compatibility by simple preliminary tests in borderline cases.To this end, the constituents are melted with stirring in the intendedmixing ratio. The melt is then cooled and observed to see whether anyclouding occurs. If any separation occurs, the expert will either haveto alter the ratio of polyamide to ethylene copolymer or will have toadd more plasticizers, more particularly hydroabietyl alcohol orcopolymers of styrene with ethylene, propylene and/or butylene, moreparticularly SEBS block polymers.

The hotmelt adhesive is preferably produced by mixing the plasticizerand the tackifying resin at 160° to 180° C. and then adding the styrenecopolymer to and dissolving it in the resulting mixture. The ethylenecopolymer, i.e. either the ethylene/vinyl acetate copolymer or theethylene/(meth)acrylate copolymer, is then added and the mixture ishomogenized. Finally, the polyamide and, lastly, the copolymer f) areadded and the mixture is further homogenized at 190° C. The hotmeltadhesive according to the invention is generally applied from the meltby means of pumps and metering units.

The melt may be stored in containers or may be obtained by melting suchmolded articles as cylinders, filaments, wires or other profiles.Immediately after application of the liquid adhesive film, the surfacesto be bonded should be pressed gently together until the actual bond hasbeen established.

In addition, it is of course possible to dissolve the new blends insuitable solvents and to apply them in this form to the surfaces to bebonded. In this case, a bondable state generally has to be establishedby application of heat. This applies in particular in cases where one ofthe two surfaces to be bonded is not permeable to the solvent used.Finally, the adhesive may also be applied in the form of a suitableaqueous dispersion and the actual bonding process may be carried out byapplication of heat after evaporation of the water.

The adhesives according to the invention are suitable for bonding anumber of substrates. For example, they may be used to bond metals suchas iron, aluminum or nickel, metal alloys, such as brass and, above all,copper which would otherwise be difficult to bond. The adhesivesaccording to the invention may also be used to bond polar and non-polarplastics, for example polyvinyl chloride, polycarbonates, polymers. Thehotmelt adhesives according to the invention are particularly suitablefor bonding non-polar polymers and, more particularly, for bondingpolyolefins, i.e. polyethylene, polypropylene and polybutylene andmixtures of these polymers, including copolymers thereof. An outstandingproperty of the systems according to the invention in this regard isthat PVC and polyethylene or metals, particularly copper, lead andaluminum, can be bonded with high strengths without the usualpretreatment, the fracture patterns in peel strength tests all beingcohesive. The PVC may even show a pronounced tendency towards theplasticizer migration.

"Without the otherwise usual pretreatment" does not mean the physicalpretreatment, for example wiping with cloths or washing with solvents,but rather the chemical pretreatment, more particularly corona treatmentand flame treatment. It is also emphasized that the individualcomponents of the polymer mixtures are completely unsuitable on theirown for establishing bonds of this type. The favorable low-temperatureproperties of the polymer blends according to the invention are also ofparticular importance. Thus, in the event of prolonged storage, noembrittlement was observed, even at temperatures of -40° C. or lower.

In addition, the viscosities and softening points lie in such rangesthat a broad range of applications can be covered. Above all, thehotmelt adhesives according to the invention may also be used forco-extrusion with polyethylene or polypropylene.

By virtue of these positive properties, the hotmelt adhesives accordingto the invention are particularly suitable for bonding plastics andmetals in the electrical industry and, in particular, for bonding cablesand lines. Sleeves, end caps, conduits and tubes, above all ofpolyethylene, coated with hotmelt adhesives are used for this purpose.They shrink on heating and, at the same time, may become tacky. A veryfirm bond is thus established after cooling. Despite the differentmaterials--some very difficult to bond, such as polyethylene andcopper--the bond established is dependable in its strength and iscapable of withstanding significant variations in temperature between-30° C. and +70° C. Other requirements, such as resistance to fungi andto rotting and non-corrosiveness, are also satisfied.

The invention is illustrated by the following Examples.

EXAMPLE 1

25 g of KRATON G 1652, a styrene/ethylene/butylene/styrene blockcopolymer (a product of Shell), are added in portions with stirring(double helical stirrer) over a period of 10 minutes at 160° to 180° C.to 120 g of ABITOL (hydroabietol, a Hercules product) and 50 g ofESCOREZ 2520 (liquid hydrocarbon resin, a product of Exxon). A clearsolution was formed in 15 minutes. After addition of 150 g of ESCORENEUL 53019 CC (ethylene/vinyl acetate copolymer, a product of Exxon), themixture was homogenized for 20-30 minutes at 180° to 190° C. 625 g ofMACROMELT 6735 (thermoplastic polyamide, a product of Henkel KGaA) werethen added over a period of 15 to 20 minutes. Finally, 30 g of EPOLENE C16 (ethylene/maleic acid copolymer, a product of Eastman) were addedover a period of 5 to 10 minutes. The whole was then stirred for 20 to30 minutes at 190° C. The hotmelt adhesive obtained had a softeningrange of 90° to 100° C. and a melt viscosity of 15,000 to 25,000 mPa.sat 160° C. Its peel strength for vPE/vPE was 140 N/25 mm (angular peeltest). The fracture showed 100% cohesive separation.

EXAMPLE 2

The test was carried out in the same way as in Example 1 with thefollowing exception: 60 g of polybutene (a product of Amoco) were usedinstead of the 120 g of ABITOL and 685 g of MACROMELT 6735 were usedinstead of the 625 g. The hotmelt adhesive obtained had the same meltingrange but a melt viscosity of 40,000 mPa.s as opposed to 35,000 mPa.sand a higher peel strength of 220 N/25 mm. The fracture was again 100%cohesive.

Comparison test

A hotmelt adhesive was produced in the same way as in Example 1 exceptthat no ABITOL or polybutene was added. A peel strength of 40 N/25 mmwas obtained. The fracture pattern was adhesive.

The measurements were carried out as follows:

1. R & B (softening point)

The softening point in °C. was measured by the ring & ball method (R &B) according to ASTM E-28.

2. Viscosity

The viscosity in mPa.s was determined using a Brookfield thermocel RVTviscosimeter (spindle 27) at 160° C. or 210° C.

3. Peel strength

Peel strength was measured by the T-peel test on non-pretreatedcrosslinked polyethylene films of extrudable 1 mm thick polymers usedfor cable manufacture.

Test specimens: 120-25 mm Overlap 50 mm

Bonding: A 1 mm thick polyamide blend film was positioned between thematerials to be bonded which were then placed in a press for 5 minutesat 150° C./7 bar.

Conditioning: 24 h at 20° C./approx. 60% relative air humidity

Test: 20° C., 50 mm crosshead speed.

4. Heat resistance (internal Henkel test)

Two 25.0 mm wide strips of flexible cardboard were bonded with a 25.0 mmoverlap. The bond was subjected to a load of 13.5N (0.02N/mm²) andexposed to a temperature increase of 5° C./10 mins. in a recirculatingair drying cabinet. The heat resistance is the temperature at which thebond remains intact.

We claim:
 1. A hotmelt adhesive comprising:a) at least 50% by weight ofthe hotmelt adhesive of at least one polyamide based on dimerized fattyacid having at least one value selected from the group consisting ofamine values of from 2 to 15 and acid values of from 1 to 50; b) 5 to20% by weight of the hotmelt adhesive of at least one copolymer ofethylene with at least one member selected from the group consisting ofvinyl acetate, acrylate, said acrylate being derived from an alcoholcontaining 1 to 18 carbon atoms, methacrylate, said methacrylate beingderived from an alcohol containing 1 to 18 carbon atoms and vinyl estersof C₃₋₁₈ carboxylic acids and copolymers wherein up to 15% of theethylene in the copolymer is replaced by propylene; c) 2 to 10% byweight of the hotmelt adhesive of at least one copolymer of styrene withat least one member selected from the group consisting of ethylene,isoprene, butadiene and butylene; and d) 5 to 25% by weight of at leastone plasticizer.
 2. The hotmelt adhesive as claimed in claim 1 furthercomprising up to 10% by weight of the hotmelt adhesive of at least onetackifying resin selected from the group consisting ofpolycyclopentadiene, polyterpene and liquid hydrocarbon resin.
 3. Thehotmelt adhesive as claimed in claim 1 further comprising up to 15% byweight of the hotmelt adhesive of at least one copolymer of maleicanhydride and at least one monomer selected from the group consisting ofethylene, propylene and butylene.
 4. The hotmelt adhesive as claimed inclaim 1 wherein said polyamide comprises residues of (i) up to 55 mole-%of at least one member selected from the group consisting of dimerizedfatty acid and a mixture of dimerized fatty acids and aliphaticdicarboxylic acids containing 4 to 12 carbon atoms, in a ratio not lessthan 1:2, (ii) up to 15 mole-% of at least one monomeric fatty acidcontaining 12 to 22 carbon atoms, (iii) up to 35 mole-% of at least onepolyether diamine of the formula:

    H.sub.2 N--R.sub.1 --O--(R.sub.2 O).sub.x --R.sub.3 NH.sub.2 (I)

wherein: x is a number of 8 to 80, R₁ and R₃ may be the same ordifferent and independently representaliphatic and cycloaliphatichydrocarbon groups, R₂ is a aliphatic hydrocarbon group containing 1 to6 carbon atoms,and (iv) up to 48 mole-% of at least one aliphatic orcycloaliphatic diamine containing 2 to 40 carbon atoms.
 5. The hotmeltadhesive as claimed in claim 4 wherein x is from 8 to 40, R₁ and R₃ eachcontain 2 to 8 carbon atoms, and R₂ is a branched aliphatic hydrocarbonradical, the amount of said dimerized fatty acid is from 35 to 39.5mole-%, the amount of said monomeric fatty acid is from 0.5 to 15mole-%, the amount of said polyether diamine is from 2 to 35 mole-%, andthe amount of said aliphatic or cycloaliphatic diamine is from 15 to 48mole-%.
 6. The hotmelt adhesive as claimed in claim 1 wherein saidpolyamide comprises residues (i) up to 55 mole-% of at least one memberselected from the group consisting of dimerized fatty acid, and amixture of dimerized fatty acids and aliphatic dicarboxylic acidscontaining 4 to 12 carbon atoms in a ratio not less than 1:2, (ii) up to15 mole % of at least one monomeric fatty acid containing 12 to 22carbon atoms, and (iii) up to 55 mole % of at least one C₂₋₄₀ aminecontaining at least two amino groups independently selected from thegroup consisting of primary and/or secondary amino groups.
 7. Thehotmelt adhesive as claimed in claim 6 wherein the amount of saiddimerized fatty acid is from 35 to 39.5 mole-%, the amount of saidmonomeric fatty acid is from 0.5 to 15 mole-%, and the amount of saidC₂₋₄₀ amine is from 45 to 55 mole-%.
 8. The hotmelt adhesive as claimedin claim 1 wherein said polyamide has an acid value of 2 to
 30. 9. Thehotmelt adhesive as claimed in claim 1 wherein said polyamide has anacid value of 4 to
 12. 10. The hotmelt adhesive as claimed in claim 1wherein said polyamide has an amine value of 4 to
 10. 11. The hotmeltadhesive as claimed in claim 1 wherein said ethylene copolymer is anethylene/vinyl acetate copolymer containing 14 to 40% of vinyl acetate.12. The hotmelt adhesive as claimed in claim 1 wherein said copolymer ofstyrene comprises a block copolymer of styrene with at least one memberselected from the group consisting of butadiene, isoprene, ethylene andbutylene.
 13. The hotmelt adhesive as claimed in claim 1 wherein saidcopolymer of styrene comprises a styrene/ethylene/butylene/styrene blockcopolymer.
 14. The hotmelt adhesive as claimed in claim 1 wherein atackifying resin is present in an amount of from 2 to 8% by weight ofthe hotmelt adhesive.
 15. The hotmelt adhesive as claimed in claim 1further comprising from 2.5 to 10% by weight of a copolymer of ethyleneor propylene with maleic anhydride.
 16. A method of bonding surfaces ofsubstrates comprising applying to at least one of the surfaces to bebonded the hotmelt adhesive as claimed in claim
 1. 17. The method asclaimed in claim 16 wherein at least one of said surfaces is anon-pretreated polyethylene or a non-pretreated polyvinyl chloridesurface.
 18. The method as claimed in claim 16 wherein said at least oneof said surfaces is polyvinyl chloride with a tendency for plasticizermigration.
 19. The method as claimed in claim 16 wherein said at leastone of said surfaces is a metal.
 20. The method as claimed in claim 16wherein said at least one of said surfaces is a member selected from thegroup consisting of copper, lead and aluminum.
 21. A shrinkable moldingcoated on at least one side with the hotmelt adhesive as claimed inclaim
 1. 22. The shrinkable molding as claimed in claim 21 wherein saidmolding is based on crosslinked polyethylene or polypropylene.
 23. Ahotmelt adhesive comprising:a) at least 50% by weight of the hotmeltadhesive of at least one polyamide based on dimerized fatty acid; b) 5to 20% by weight of the hotmelt adhesive of at least one ethylenecopolymer selected from the group consisting of ethylene/vinyl acetatecopolymer, ethylene/acrylate copolymer, said acrylate being derived froman alcohol containing 1 to 18 carbon atoms, and ethylene/methacrylatecopolymer, said methacrylate being derived from an alcohol containing 1to 18 carbon atoms; c) 2 to 10% by weight of the hotmelt adhesive of atleast one copolymer of styrene with at least one member selected fromthe group consisting of ethylene, isoprene and butylene; d) 5 to 25% byweight of the hotmelt adhesive of at least one plasticizer; e) up to 10%by weight of the hotmelt adhesive of at least one tackifying resinselected from the group consisting of polycyclopentadiene, polyterpeneand, liquid hydrocarbon resin and f) up to 15% by weight of the hotmeltadhesive of at least one copolymer of monomers selected from the groupconsisting of ethylene, propylene, butylene and maleic anhydride.
 24. Aprocess for the production of a hotmelt adhesive as claimed in claim 23comprising adding component c) to a mixture of components d) and e) anddissolving said component c) in said mixture of components d) and e),adding component b) to the resulting mixture of components c), d), ande) and homogenizing the resulting mixture of components b), c), d), ande) and, finally, adding components a) and f) to said mixture ofcomponents b), c), d), and e) and homogenizing the resulting mixture ofcomponents a), b), c), d), e), and f).